Transgenerational plasticity to warming decreases nutrient release by a keystone grazer

Sarah Hasnain, Valerie McCarthy, Cihelio Alves Amorim, Lucia Cabrera-Lamanna, Emma Drohan, Zeynep Dilbe-Uyar, Gülce Yalçın, Dilvin Yıldız, Meryem Beklioğlu, Kemal Ali Ger

Human-driven environmental change can reshape species traits via evolutionary adaptation and plasticity. Yet, how stress-induced plasticity, especially trans-generational responses, cascades to ecosystem processes remains unknown. In particular, warming can lead to marked effects on fitness via trans-generational plasticity (TGP), yet how such changes affect ecosystem functioning is not well understood. Here, we used reciprocal transplant experiments to examine if warming triggers TGP impacts on grazing and fluxes in nitrogen (N) and phosphorus (P) by the keystone freshwater grazer Daphnia magna. Individuals were reared for two generations at either 18°C or 24°C. Offspring from the second generation were exposed to either 18°C or 24°C and we quantified algal clearance, and nutrient uptake and release responses. Our results show that warmer maternal temperature exposure did not alter grazing rates. However, warmer maternal temperatures elevated body P content in offspring and altered nutrient release, thereby increasing the ratio of dissolved N:P in the system. These results suggest that TGP can shift body stoichiometry and nutrient release patterns under warming, with potentially strong consequences for N and P cycling in lake ecosystems.